Requiem for a Whistleblower

Maybe she deserved to die...
In a London park, Gayle Patterson, a former teacher, is found dead with stab wounds.
Detective Inspector Benedict Paige's investigations lead to a 25-year-old called Colin. The murder weapon is recovered from Colin's garden, and, under questioning, he confesses to killing Gayle.
The problem is that Colin has the mental age of a seven-year-old, casting doubt on his ability to comprehend the severity of his actions and his culpability.
Colin's older brother, Roger, has his own problems with the police. Wanted for dealing with stolen goods, is he manipulating his vulnerable sibling?
DI Paige discovers Roger and Gayle had been lovers. This family is clearly implicated.
As a teacher, Gayle had her enemies, and it soon becomes clear that there were several individuals who had reasons to want Gayle dead. She'd lied, blackmailed and used people.
Had her past caught up with her?
As DI Paige delves deeper, he finds a toxic mix of bitterness, revenge and jealousy lurking beneath the surface.